A NASA satellite has measured the amount of pollution from East Asian forest fires, urban exhaust, and industrial production that makes its way to western North America.
Hongbin Yu, an associate research scientist of the University of Maryland Baltimore County, teamed with other researchers to take advantage of the innovations in satellite technology and has now made the first-ever satellite-based estimate of pollution aerosols transported from East Asia to North America.
The new measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite substantiate the results of previous model-based studies, and are the most extensive to date.
The MODIS instrument can distinguish between broad categories of particles in the air, and observes Earth's entire surface every one to two days, enabling it to monitor movement of the East Asian pollution aerosols as they rise into the lower troposphere, the area of the atmosphere where we live and breathe, and make their way across the Pacific and up into the middle and upper regions of the troposphere.
Yu and his colleagues measured the trans-Pacific flow of pollution in teragrams, a unit of measurement of the mass of pollution aerosol.
Satellite data confirmed 18 teragrams - almost 40 billion pounds - of pollution aerosol was exported to the northwestern Pacific Ocean and 4.5 teragrams - nearly 10 billion pounds - reached North America annually from East Asia over the study period.
According to Yu, "We used the latest satellite capabilities to distinguish industrial pollution and smoke from dust transported to the western regions of North America from East Asia."
"Looking at four years of data from 2002 to 2005, we estimated the amount of pollution arriving in North America to be equivalent to about 15 percent of local emissions of the U.S. and Canada," he said.
"This is a significant percentage at a time when the U.S. is trying to decrease pollution emissions to boost overall air quality. This means that any reduction in our emissions may be offset by the pollution aerosols coming from East Asia and other regions," said Yu.
"Satellite instruments give us the ability to capture more accurate measurements, on a nearly daily basis across a broader geographic region and across a longer time frame so that the overall result is a better estimate than any other measurement method we've had in the past," said study co-author Lorraine Remer, a physical scientist and member of the MODIS science team at NASA Goddard.